The standard grips this chord is usually shown with.
F#maj9 is F#, A#, C#, E# and G# — F#maj7 with the ninth stacked above it.
It sounds a maj7 with more air in it. The ninth argues with nothing here, so it works anywhere a maj7 does.
Tonic — an extended resting chord.

| F# | A# | C# | E# | G# |
|---|---|---|---|---|
| 1 | 3 | 5 | 7 | 9 |
Also written F#M9, F#Δ9, F#ma9 or F# major 9. The same chord either way; which spelling you meet depends on who wrote the chart.
F#maj9 in 1st inversion puts A# in the bass instead of F#, the 3rd of the chord. The notes are the same; what changes is what the bass line does, which is most of why you would reach for it — it lets the lowest voice move by step where the root would have jumped.
One of F#maj9’s 12 common shapes does this:644664
Play F#maj9 as a shell — root, third and seventh — and the spare string takes the #11 (B#) or the 13 (D#).
All 12 common shapes as fret numbers, lowest string first. Hover or tap one to see it drawn.
How you get to it. The turn that lands on F#maj9 is G#m7 to C#7 — the ii and the V of F# — and C#7 shares its third and seventh with G#m7, so the hand barely moves between them.
In which keys. Every note of F#maj9 belongs to C# major (the IV, the subdominant), Eb minor (the ♭III), F# major (the I, the tonic) and Bb minor (the ♭VI).
Every note of F#maj9 is in F# major and F# lydian.
Change one note of F#maj9 and you have F#maj7 (drop the ninth), F#maj11 (add the eleventh), F#maj13 (add the thirteenth), F#mMaj9 (the major third becomes the minor third), F#add9 (drop the major seventh) or F#69 (the major seventh becomes the sixth).
F#maj9 is a major chord — root, major third, fifth. Major chords on every root.
The common shapes and the derived voicings come from different places, and both are explained in how this site is built.
Shows each chord the way this style would voice it, and marks which of its alternatives belong to the idiom.